The goal of this project is to characterize the immune response to virus components and other antigens expressed on the surface of infected cells. The function of histocompatibility antigens in forming the target of the immune response is being assessed. Monoclonal antibodies to a major surface component of measles virus, the hemagglutinin, have been produced and used to characterize the biosynthesis, glycosylation and insertion of this protein. Syngeneic anti-idiotypic antibodies directed at monoclonal anti-hemagglutinin antibodies have been produced and are being used to seek major cross-reactive idiotypes. The interaction between anti-idiotypes and the anti-viral immune response is being investigated as well as the regulation of individual idiotypes.